1. Field
Embodiments of the present invention relate to an electric brake system which has a simplified structure and allows precise pressure control.
2. Description of the Related Art
A brake system for braking of a vehicle is essentially mounted on a vehicle, and various systems have recently been proposed to obtain stronger and more stable braking force. Examples of brake systems include an anti-lock braking system (ABS), a brake traction control system (BIOS), and a vehicle dynamic control system (VDC). The ABS prevents wheels from skidding upon braking. The BTCS prevents slippage of driving wheels during rapid acceleration from a stop or upon sudden acceleration of a vehicle. The VDC maintains a stable driving state of a vehicle by controlling a brake oil pressure through a combination of the ABS and the BTCS.
Such an electric brake system includes a plurality of solenoid valves to control a braking oil pressure transmitted to a wheel cylinder (a hydraulic brake) mounted on a wheel of a vehicle, a pair of a low-pressure accumulator and a high-pressure accumulator to temporarily store oil flowing out of the wheel cylinder, a motor and a pump to forcibly pump the oil in the low-pressure accumulator, a plurality of check valves to prevent reverse flow of the oil, and an electronic control unit (ECU) to control the operations of the solenoid valves and the motor. These constituents are compactly installed in a hydraulic block formed of aluminum.
The structure of such a brake system is disclosed in Korean Patent No. 10-1090910. According to this document, the brake system drives the motor and the pump to fill the high-pressure accumulator and/or the low-pressure accumulator with hydraulic pressure and controls increase, decrease and maintenance of the hydraulic pressure by opening and closing the electric solenoid valves. Accordingly, the structure of the brake system is complex.
In addition, there is a predetermined gap between an input rod, which applies pressure to a master cylinder according to foot force applied to the brake pedal, and the master cylinder. Accordingly, when a driver operates the brake system, a lost travel section of pedal stroke is produced. This may cause the driver to feel that the brake is not functioning properly and be dissatisfied with braking, and may even lead to an accident. Further, pedal feel may be degraded.